The proposed research will develop a system for genetic manipulation of Bacteroides and map key metabolic and antibiotic resistance loci on the chromosome of B. fragilis. Bacteroides are the most numerous bacteria in the normal human colon as well as the major pathogens in anaerobic infections. This study will characterize the conjugation system of pBF4, a self-transmissible drug resistance plasmid from B. fragilis. The pBF4 transfer system will be integrated into the Bacteroides chromosome, generating Hfr-like strains that transfer chromosomal loci. Nutritional auxotrophs and drug resistant strains will be used to generate a genetic map of the Bacteroides chromosome, providing important information about the transfer mechanism of anaerobic resistance plasmids and delineating the chromosomal organization of genes involved in key metabolic and drug resistance functions.